WO2016067398A1

WO2016067398A1 - Scanning probe microscope and sample observation method using same

Info

Publication number: WO2016067398A1
Application number: PCT/JP2014/078804
Authority: WO
Inventors: 中田　俊彦; 修一馬場
Original assignee: 株式会社日立製作所
Priority date: 2014-10-29
Filing date: 2014-10-29
Publication date: 2016-05-06

Abstract

The purpose of the present invention is to greatly reduce background noises and improve the efficiency of the generation of near-field light in a scanning probe microscope. A scanning probe microscope is equipped with: a measurement probe for scanning over and in relation to a sample to be inspected; an exciting light irradiation system; a (near-field light for excitation)-generating system for irradiating an area including the measurement probe with exciting light from the exciting light irradiation system to generate near-field light for excitation in the area; and a scattered light detection system for detecting scattered light of near-field light for measurement which is generated between the measurement probe and the sample by the action of the near-field light for excitation.

Description

Scanning probe microscope and sample observation method using the same

The present invention relates to a scanning probe microscope technique and a sample observation method using the same.

A near-field scanning microscope (SNOM: Scanning Near-field Optical Microscope) is known as a means for measuring optical properties and physical property information of a sample surface with high resolution. As disclosed in Non-Patent Document 1, this microscope irradiates a metal probe with a laser beam from the outside, and is scattered by a small tip (several tens of nm) of the probe. By scanning the near-field light with a gap of tens of nanometers in the same manner (scattering probe), the resolution of the tens of nanometers is as large as the tip of the probe beyond the diffraction limit of light. Thus, optical properties such as reflectance distribution and refractive index distribution on the sample surface are measured.

As a similar technique, Patent Document 1 discloses that a plasmon enhanced near-field probe having a nanometer-order optical resolution is formed by combining nanotubes and metal nanoparticles as a measurement probe with a metal structure embedded therein. Mounted in a high-efficiency plasmon excitation unit and repeatedly approaching and retracting with low contact force at each measurement point on the sample, with a resolution on the order of nanometers without damaging both the probe and the sample The optical information and unevenness information on the sample surface are measured with high reproducibility and high S / N ratio "(summary).

JP 2010-197208 A

In the near-field scanning microscope disclosed in Non-Patent Document 1, not only the scattered light generated by the interaction between the near-field light excited by the laser beam and the sample but also the laser beam is irradiated to the metal probe. Most of the laser light is scattered at the base of the metal probe, the cantilever holding the metal probe, or the sample surface, and very strong scattered light is generated. As a result, these scattered lights are superimposed on the near-field light image as background noise, which is a factor that degrades the SN ratio, contrast, and measurement reproducibility of the near-field light image.

Therefore, in Patent Document 1, laser light is converted into surface plasmon, and this surface plasmon is propagated to the tip of a carbon nanotube (CNT: Carbon Nanotube) enclosing a metal nanostructure to generate near-field light at the tip of the CNT. A method is disclosed. However, in this method, the conversion efficiency of laser light into surface plasmons and the generation efficiency of near-field light are not practically sufficient, and as a result, the SN ratio, contrast, and measurement reproducibility of the near-field light image are reduced. ing.

Accordingly, an object of the present invention is to provide a scanning probe microscope capable of solving the above-described problems, greatly reducing background noise, and improving near-field light generation efficiency, and a sample observation method using the same. There is.

In order to achieve the above object, one of the typical scanning probe microscopes of the present invention includes a measurement probe that relatively scans a sample to be examined, an excitation light irradiation system, and an excitation light irradiation system. An excitation near-field light generating system that generates excitation near-field light in a region including the measurement probe by irradiation of excitation light, and the excitation near-field light is generated between the measurement probe and the sample. And a scattered light detection system for detecting the scattered light of the near-field light for measurement.

In addition, one of the sample observation methods using the scanning probe microscope of the present invention typically includes scanning the measurement probe relative to the sample to be inspected and including the measurement probe by irradiation with excitation light. Generate near-field light for excitation in a region, generate near-field light for measurement between the measurement probe and the sample by the near-field light for excitation, and detect scattered light of the near-field light for measurement Is.

According to the present invention, it is possible to greatly reduce background noise, improve the generation efficiency of near-field light, and improve the SN ratio, contrast, and measurement reproducibility. Can be obtained.

FIG. 5 is a perspective view of a Si cantilever-mounted gold-coated Si chip and a probe fixed to the tip of the chip in Examples 1 to 4. It is a side view which shows the optical path in the chip | tip of the gold coat Si chip | tip in Example 1, the probe fixed to the chip | tip tip, and the laser beam for excitation. 6 is a graph showing the relationship (plasmon resonance curve) between the angle of incidence of excitation laser light on the gold / Si interface and the surface reflectance with the gold film thickness in Examples 1 to 3 as a parameter. FIG. 6 is a front view showing a structure of a CNT probe filled with gold nanoparticles in Examples 1 to 4. FIG. 6 is a front view showing the structure of a CNT probe in which gold nanoparticles are filled at the tip in Examples 1 to 4. FIG. 6 is a front view showing the structure of a CNT probe without a filler and having a tip closed with carbon in Examples 1 to 4. FIG. 6 is a front view showing a structure of a CNT probe in which a gold thin film is coated on a surface or a part including a tip portion of CNT in Examples 1 to 4. FIG. 6 is a front view showing the structure of a metal tip such as a Si probe, an HDC (High Density Carbon) probe, or a gold, silver, or aluminum with a sharpened tip in Examples 1 to 4. FIG. 5 is a block diagram illustrating a schematic configuration of a scanning probe microscope in Example 1 and Example 3. FIG. 6 is a block diagram showing a schematic configuration of a scanning probe microscope in Example 2 and Example 3. It is a side view which shows the optical path in the chip | tip of the gold coat Si chip | tip in Example 3, the probe fixed to the chip | tip tip, and the laser beam for excitation. It is a side view which shows the optical path in the chip | tip of the gold coat Si chip | tip in Example 4, the probe fixed to the chip | tip tip, and the laser beam for excitation. It is a graph which shows the relationship between the thickness of Si layer in Example 4, and the transmittance | permeability of each wavelength. It is a graph which shows the relationship (plasmon resonance curve) with the incident angle to the aluminum / Si interface of the excitation laser beam of each wavelength, and a surface reflectance by using the aluminum film thickness in Example 4. FIG. 10 is a block diagram showing a schematic configuration of a scanning probe microscope in Example 4. FIG. 10 is a block diagram showing a schematic configuration of a scanning probe microscope in Example 4.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing for explaining the embodiment, elements having the same function are given the same name and reference numeral, and repeated explanation thereof is omitted.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a Si cantilever-mounted gold-coated Si chip and a probe fixed to the tip of the first embodiment. A triangular pyramid-shaped Si chip 2 coated with a gold thin film 3 is fixed to the tip of the Si cantilever 4, and a carbon nanotube (CNT: Carbon Nanotube) probe 1 is fixed to the tip of the chip.

Here, the material of the chip 2 is not limited to Si, and may be SiO ₂ , Si ₃ N ₄ or the like as long as it is a material that transmits laser light having a specific wavelength. The gold thin film 3 may be a film made of another material as long as it is a metal material that shields laser light depending on the film thickness, and may be, for example, an aluminum or silver film.

As shown in FIGS. 1 and 2, from the back surface of the Si cantilever 4, for example, excitation laser light 5 having a wavelength of 850 nm as excitation light is irradiated onto the plane of the rear gold thin film 3 b of the triangular pyramidal gold-coated Si chip 2. When reflected on the rear plane and condensed on the front ridge line, surface plasmons (collective vibrations of gold free electrons) 9 are excited on the ridge line of the gold thin film 3a as shown in FIG. Here, FIG. 3 shows a plot of the relationship between the incident angle θ7 of the excitation laser beam 5 with respect to the ridgeline of the gold thin film 3a and the reflected light intensity from the incident point, that is, the reflectance at the gold / Si interface. In FIG. 3, d is the film thickness 8 of the gold thin film 3a. As shown in FIG. 3, when the wavelength is 850 nm, strong plasmon resonance occurs at the gold / Si interface near an incident angle of 16.12 °, and the reflectance is minimum when the film thickness d of the gold thin film 3a is 46.5 nm, that is, plasmon resonance. It turns out that becomes the maximum. That is, in FIG. 2, the intensity of the surface plasmon 9 is maximized by setting the incident angle θ7 to 16.12 ° with respect to the excitation laser beam 5 and setting the film thickness d8 of the gold thin film 3a to 46.5 nm. . The surface plasmon 9 propagates toward the tip of the gold-coated Si chip 2, and the excitation near-field light (first near-field light) localized at the tip 2 of the tip of the chip 2 within a range of several hundreds of nanometers that is almost the same size as the tip of the chip. ) 10 is generated. The tip of the CNT probe 1 is present in the electric field of the excitation near-field light 10.

FIG. 4 shows an example of the structure of the CNT probe 1. The CNT probe 1 has a length of 2 to 3 m, an outer diameter of φ20 nm, an inner diameter of φ4 nm, and a multi-layer CNT sharpened to a tip of about φ4 nm as a base, and has an inner diameter of φ4 nm along the axial direction of the measurement probe. Gold nanoparticles 11 are filled. The filler is not limited to gold nanoparticles. Depending on the wavelength of the laser light used, for example, gold nanoparticles can be used for near-infrared light, alumina nanoparticles or silver nanoparticles can be used for visible light, and alumina nanoparticles can be used for ultraviolet light. Further, instead of nanoparticles, nanorods may be used. In addition, as shown in FIG. 5, when the structure in which the CNT tips are filled with gold nanoparticles 11a or the generation efficiency of near-field light is low, there is no problem, as shown in FIG. A closed structure may be used. Further, as shown in FIG. 7, a structure in which a metal thin film 14 such as gold, silver, or aluminum is coated on the surface or a part including the tip of the CNT may be used. Furthermore, the probe material is not limited to CNT. For example, as shown in FIG. 8, a Si probe 15 having a sharp tip, a HDC (High Density Carbon) probe 15, gold, silver, aluminum, for example. A metal probe 15 such as can also be used.

As shown in FIG. 2, these

probes

1 and 15 are fused and fixed on the ridge line of the gold-coated Si chip 2 using three gold dots 16 formed by electron beam selective CVD (Chemical Vapor Deposition) as a binder. The The dots 16 are not limited to gold, and may be carbon or tungsten. The protruding length of the

probes

1 and 15 from the tip of the gold-coated Si chip 2 is adjusted to, for example, 50 to 200 nm so that the tip of the probe exists in the electric field of the excitation near-field light 10. By concentrating the electric field at the tip, near-field light for measurement (second near-field light) 6 having a diameter of about 4 nm (spot size) that is the same as the tip diameter is generated at the tip of the probe. In particular, as shown in FIG. 4, in the case of a structure in which gold nanoparticles 11 are filled in the CNT, or in a structure in which a gold thin film 14 is coated on the CNT surface as shown in FIG. Propagating along the nanoparticles 11 and the gold thin film 14, the electric field concentrates at the tip of the CNT probe 1, and the very strong near-field light 6 is excited together with the electric field concentration of the excitation near-field light 10.

As shown in FIGS. 4 to 8, the near-field light 6 interacts with the surface of the sample 20 and the

probes

1 and 15 themselves, and scattered light (propagating light) 13 is generated. The intensity of the scattered light varies depending on the magnitude relationship between the refractive index n ₀ of the region 21 constituting the sample 20 and the refractive index n ₁ of the region 22, and this is the proximity obtained by scanning the

probes

1 and 15. It becomes the contrast of the field light image. The resolution of the near-field light image is 4 nm which is substantially the same as the spot size of the measurement near-field light (second near-field light) 6.

As shown in FIG. 2, the excitation laser beam 5 is incident on the ridge line of the gold-coated Si chip 2 at a plasmon resonance angle of 16.12 °. Since the existing near-intensity light (first near-field light) 10 having the maximum intensity is generated, the near-field light for measurement (second near-field light) 6 having the maximum intensity at the tips of the

probes

1 and 15 is generated. Can be generated. Furthermore, the configuration is such that the measurement near-field light (second near-field light) 6 is generated by the excitation near-field light (first near-field light) 10 that is localized in the range of several hundreds of nanometers. Scattered light is drastically reduced and background noise is greatly reduced.

FIG. 9 shows the configuration of a scanning probe microscope based on the principle described above. The scanning probe microscope includes a sample holder 25 on which the sample 20 is mounted, an XY piezoelectric element stage 30 on which the sample holder 25 is mounted and which scans the sample 20 in the X and Y directions relative to the measurement probe, and the sample 20 on the tip. The Si cantilever 4 mounted with the gold-coated Si chip 2 on which the

probes

1 and 15 are fixed, the piezoelectric cantilever 4 for slightly vibrating the Si cantilever 4 in the Z direction, and the Si cantilever 4 relative to the sample 20. A Z piezoelectric element stage 33 that scans in the Z direction, an optical lever detection system 100 that detects the contact force between the CNT probe and the sample by detecting the deflection of the cantilever 4, and a wavelength of 850 nm using a near infrared semiconductor laser as a light source. The excitation laser beam irradiation system 50 for irradiating the gold-coated Si chip 2 with the excitation laser beam 5 through the back surface of the Si cantilever 4 and the scattered light 13 are collected. Configured as a scattered light detecting system 110 for photoelectrically converting, and a signal processing and control system 120 for generating and outputting a near-field optical image and the surface unevenness image from the obtained scattered light signals and the XYZ displacement signal. The XY piezoelectric element stage 30 and the Z piezoelectric element stage 33 constitute a drive unit that scans the

probes

1 and 15 relative to the sample 20.

In the optical lever detection system 100, the back surface of the cantilever 4 is irradiated with the laser light 36 from the semiconductor laser 35, the reflected light is received by the quadrant sensor 37, and the deflection amount of the cantilever 4 is detected from the change in position of the reflected light. Further, the Z piezoelectric element stage is detected by the control unit 80 of the signal processing / control system 120 so that the contact force between the

probes

1 and 15 and the sample 20 is detected from the deflection amount, and the contact force always becomes a preset value. 33 is feedback controlled.

The

probes

1 and 15 are vibrated minutely in the Z direction at the resonance frequency of the cantilever 4 by the piezoelectric element actuator 34 based on the signal from the oscillator 60, so that the generated near-field light 6 and scattered light 13 are also intensities at the same frequency. Modulated. The scattered light 13 is condensed by a condensing lens 41 at one point on the light receiving surface 43 of a detector 42 such as a photomultiplier tube or a photodiode and is photoelectrically converted.

The intensity-modulated scattered light signal output from the detector 42 is synchronously detected by the lock-in amplifier 70 of the signal processing / control system 120, and only this frequency component is output. The background scattered light slightly directly scattered on the sample surface by the excitation laser beam 5 does not react to the minute vibration of the cantilever 4 and is a direct current component, and thus is not included in the output signal of the lock-in amplifier 70. Thus, it is possible to selectively detect only the near-field light component while suppressing the remaining background noise. Further, the signal SN ratio can be further improved by detecting harmonic components such as the second harmonic and the third harmonic of the resonance frequency. The scattered light signal from the lock-in amplifier 70 is sent to the control unit 80 of the signal processing / control system 120, combined with the XY signal from the XY piezoelectric element stage 30 to generate a near-field light image, and output to the display 90. The At the same time, the Z signal from the Z piezoelectric element stage 33 is also combined with the XY signal by the control unit 80 to generate an uneven image on the sample surface and output to the display 90.

According to the present embodiment, as described above, the excitation laser beam 5 is incident on the ridge line of the gold-coated Si chip 2 at a plasmon resonance angle of 16.12 °, whereby the surface plasmon 9 having the maximum intensity can be excited. Since the excitation near-field light (first near-field light) 10 having the maximum intensity localized at the tip portion is generated, the measurement near-field light (second proximity light) having the maximum intensity is generated at the tips of the

probes

1 and 15. (Field light) 6 can be generated. Furthermore, the configuration is such that the measurement near-field light (second near-field light) 6 is generated by the excitation near-field light (first near-field light) 10 that is localized in the range of several hundreds of nanometers. Scattered light is drastically reduced and background noise is greatly reduced. As a result, it is possible to obtain a near-field light image having a resolution of nanometer order (a size similar to the probe tip diameter) with improved SN ratio, contrast, and measurement reproducibility.

A second embodiment of the present invention will be described with reference to FIG.
In the first embodiment, the scattered light 13 on the surface layer of the sample 20 of the measurement near-field light 6 at the tips of the

probes

1 and 15 is detected. In this embodiment, the measurement of the tips of the

probes

1 and 15 is measured. Of the scattered light on the surface layer of the sample 20 of the near-field light 6 for use, the scattered light 13 transmitted through the sample 20 is detected. That is, the scattered light 13 is condensed by the condensing lens 41 at one point on the light receiving surface 43 of the detector 42 such as a photomultiplier tube or a photodiode and is photoelectrically converted. The XY piezoelectric element stage 31 that places the sample holder 26 and scans the sample 20 in the XY direction has a structure in which a hole is opened in the center in order to transmit the transmitted scattered light. The configurations and functions of the other excitation laser beam irradiation system 50, optical lever detection system 100, and signal processing / control system 120 are the same as those in the first embodiment, and thus description thereof is omitted.

According to the present embodiment, as described above, the excitation laser beam 5 is incident on the ridge line of the gold-coated Si chip 2 at a plasmon resonance angle of 16.12 °, whereby the surface plasmon 9 having the maximum intensity can be excited, and the tip of the chip 2 Since the excitation near-field light (first near-field light) 10 having the maximum intensity localized in the portion is generated, the measurement near-field light (second near-field light) having the maximum intensity is generated at the tips of the

probes

1 and 15. Light) 6 can be generated. Furthermore, the configuration is such that the measurement near-field light (second near-field light) 6 is generated by the excitation near-field light (first near-field light) 10 that is localized in the range of several hundreds of nanometers. Scattered light is drastically reduced and background noise is greatly reduced. As a result, it is possible to obtain a near-field light image having a resolution of nanometer order with improved SN ratio, contrast, and measurement reproducibility.

In addition, according to the present embodiment, since the scattered light is not interrupted by the Si cantilever, the XY piezoelectric element stage 31, and the Z piezoelectric element stage 33, the detection solid angle can be increased and imaging can be performed with higher contrast than in the first embodiment. The SN ratio and measurement reproducibility of the field light image can be further improved.

A third embodiment of the present invention will be described with reference to FIG. In the first and second embodiments, as shown in FIG. 2, the excitation laser beam 5 is incident on the ridge line of the gold-coated Si chip 2 at a plasmon resonance angle of 16.12 °. In the example, as shown in FIG. 11, the excitation laser beam 5 having a wavelength of 850 nm is incident on the plane of the rear gold thin film 3b of the triangular pyramidal gold-coated Si chip 2, and the incident angle θ7 is as shown in FIG. In addition, the angle is set to 16.12 °, and the film thickness d8 of the gold thin film 3b is set to 46.5 nm. At this time, the excitation laser beam 5 is incident on the back surface of the Si cantilever 4 at a very shallow angle, and the configuration of the excitation laser beam irradiation system 50 becomes extremely difficult. Therefore, in this embodiment, as shown in FIG. 11, the upper end portion of the triangular pyramidal gold-coated Si chip 2 is processed to a desired angle by FIB (Focused Ion Beam), and the excitation laser beam 5 is refracted on the processed surface. By doing so, the light is incident on the plane of the rear gold thin film 3b at a plasmon resonance angle of 16.12 °. As a result, the intensity of the surface plasmon 9 is maximized. The surface plasmon 9 propagates toward the tip of the gold-coated Si chip 2, and the excitation near-field light (first near-field light) localized at the tip 2 of the tip of the chip 2 within a range of several hundreds of nanometers that is almost the same size as the tip of the chip. ) 10 is generated. In the electric field of the excitation near-field light 10, the tips of the

probes

1 and 15 are present. In the first and second embodiments, the incident angle of the excitation laser beam 5 with respect to the ridgeline of the gold-coated Si chip 2 is a plasmon resonance angle of 16.12 °, but the gold / Si interface on the side wall portion sandwiching the ridgeline Is deviated from the plasmon resonance angle. For this reason, not all of the incident excitation laser beam 5 is converted into surface plasmons, and a loss occurs. On the other hand, in the present embodiment, the excitation laser beam 5 is incident on the rear gold thin film 3b plane of the Si chip 2, so that almost all of the excitation laser beam 5 is incident at a plasmon resonance angle of 16.12 °. Thus, almost all of the excitation laser beam 5 can be converted into the surface plasmon 9. As a result, the intensity of the excitation near-field light (first near-field light) 10 generated at the tip of the chip 2 is significantly higher than in the first and second embodiments. As a result, the near-field light for measurement (second proximity) is much larger at the tips of the

probes

1 and 15 existing in the electric field of the excitation near-field light 10 than in the first and second embodiments. Field light) 6 is generated.

The configuration and function of the

probes

1 and 15 are the same as those shown in FIGS. 4 to 8, and the configuration and function of the scanning probe microscope equipped with the Si cantilever 4 based on the above principle is shown in FIG. 9 or FIG. Since it is the same as that, a description thereof will be omitted.

According to the present embodiment, as described above, the excitation laser beam 5 is incident on the rear gold thin film 3b plane of the gold-coated Si chip 2 at a plasmon resonance angle of 16.12 °, whereby the first and second The surface plasmon 9 that is much larger than the embodiment can be excited. As a result, the excitation near-field light (first near-field light) 10 that is much larger than the first and second embodiments is generated at the tip end of the tip 2. It is possible to generate a measurement near-field light (second near-field light) 6 that is significantly larger at the tip than in the first and second embodiments. Furthermore, the configuration is such that the measurement near-field light (second near-field light) 6 is generated by the excitation near-field light (first near-field light) 10 that is localized in the range of several hundreds of nanometers. Scattered light is drastically reduced and background noise is greatly reduced. As a result, it is possible to obtain a near-field light image having a resolution of nanometer order with improved SN ratio, contrast, and measurement reproducibility.

A fourth embodiment of the present invention will be described with reference to FIGS. In the first to third embodiments, monochromatic light having a wavelength of 850 nm is used as the excitation laser beam 5, but in this embodiment, a plurality of wavelengths of R (Red), G (Green), and B (Blue) are used. For example, color imaging is realized. As shown in FIG. 12, for example, excitation laser light 5a having a wavelength of 488 nm, excitation laser light 5b having a wavelength of 532 nm, and excitation laser light 5c having a wavelength of 660 nm are used as a plurality of wavelengths. At this time, as shown in FIGS. 2 and 11, when light in the visible region is propagated through the Si chip 2, the excitation efficiency of the surface plasmon is greatly attenuated due to absorption by Si. Therefore, as shown in FIG. 12, the upper end portion of the Si chip 2 is subjected to FIB processing, and the Si layer on the rear plane portion is thinned. For example, as shown in FIG. 13, when the thickness d _s 18 of the Si layer is 250 nm, a sufficient transmittance of about 60% at a wavelength of 488 nm, 77% at 532 nm, and 93% at 660 nm can be obtained. Furthermore, in order to express surface plasmon in the visible range, an aluminum thin film 47 is coated on the surface of the triangular pyramidal Si chip 2 instead of the gold thin film. Similarly, it is desirable to change the filling material of the

probes

1 and 15 and the coating material on the surface from gold to aluminum. By making the FIB processing surface a desired angle and further adjusting the incident angles of the three wavelength

excitation laser beams

5a, 5b, and 5c to the processing surface, and refracting each excitation laser beam at a desired angle, Three-wavelength

excitation laser beams

5a, 5b, and 5c can be incident on the plane of the rear aluminum thin film 47b at different plasmon resonance angles θ7a, 7b, and 7c. As shown in FIG. 14, the plasmon resonance angle of each wavelength at the aluminum / Si interface is 13.49 ° at a wavelength of 488 nm, 14.18 ° at 532 nm, and 15.30 ° at 660 nm. Further, the aluminum film thickness d8 at which the reflectance is minimized almost evenly at three wavelengths, that is, where strong plasmon resonance occurs, is 15 nm. As described above, the

surface plasmons

9a, 9b, 9c corresponding to the respective wavelengths propagate toward the tip of the aluminum-coated Si chip 2, and are localized at the tip of the chip 2 within a range of several hundreds of nanometers, which is approximately the same size as the tip of the chip. The existing excitation near-field light (first near-field light) 10a, 10b, 10c is generated. The tips of the

probes

1 and 15 exist in the electric field of the excitation near-

field light

10a, 10b, and 10c. As a result, three-wavelength measurement near-field light (second near-field light) 6a and 6b are formed at the tips of the

probes

1 and 15 existing in the electric fields of the excitation near-

field lights

10a, 10b, and 10c. , 6c are generated. As the material of the chip, Si is mainly used because it is easy to manufacture by anisotropic etching, but it is also possible to use a material transparent to visible light such as Si ₃ N ₄ . In that case, a chip having a structure as shown in FIG. 11 can be used. Also in this case, by adjusting the incident angles of the three-wavelength

excitation laser beams

5a, 5b, and 5c to the processed surface and refracting each excitation laser beam at a desired angle, the plane of the rear aluminum thin film 47b is adjusted. On the other hand, three-wavelength

excitation laser beams

5a, 5b, and 5c are made incident at different plasmon resonance angles θ7a, 7b, and 7c.

Since the configuration and function of the

probes

1 and 15 are the same as those shown in FIGS. 15 and 16 show the configuration of a scanning probe microscope equipped with the Si cantilever 4 based on the above principle. The function and configuration of the scanning probe microscope shown in FIGS. 15 and 16 are basically the same as those shown in FIGS. 9 and 10, but the configuration of the excitation laser light irradiation system 50 and the scattered light 13 are condensed. The configuration of the scattered light detection system 110 that performs photoelectric conversion is different. That is, as shown in FIGS. 15 and 16, the excitation laser beam irradiation system 51 is equipped with a three-wavelength solid-state laser, and the laser beam of each wavelength is applied to the processed surface of the aluminum-coated Si chip as shown in FIG. Three excitation laser beams are emitted so as to have a desired incident angle. The intensity-modulated

scattered lights

13a, 13b, and 13c corresponding to the three wavelengths are collected at a single point 44 by a condenser lens 41, and then a wavelength of 488 nm by a wavelength separation optical system 45 including a dichroic mirror and an interference filter. The wavelength components are separated into three wavelength components of 532 nm and 660 nm, and each wavelength component is photoelectrically converted by a detector 46 including three photomultiplier tubes and photodiodes. The intensity-modulated three-wavelength scattered light signals output from the detector 46 are synchronously detected by the three lock-in amplifiers 70 of the signal processing / control system 120, and only this frequency component is output. The scattered light signals from the three lock-in amplifiers 70 are sent to the control unit 80 of the signal processing / control system 120 and combined with the XY signals from the XY piezoelectric element stage 30 to generate a three-wavelength near-field light image. Is output to the display 90. At the same time, the Z signal from the Z piezoelectric element stage 33 is also combined with the XY signal by the control unit 80 to generate an uneven image on the sample surface and output to the display 90. It is also possible to synthesize a near-field light image of three wavelengths RGB to generate a near-field color image and output it to the display 90.

According to the present embodiment, as described above, the

excitation laser beams

5a, 5b, and 5c are incident on the rear aluminum thin film 47b plane of the aluminum-coated Si chip 2 at the plasmon resonance angle for each of the three wavelengths. In addition,

surface plasmons

9a, 9b, and 9c that are much larger than those of the second embodiment can be excited. As a result, the excitation near-field light (first near-field light) 10a, 10b, and 10c, which is much larger than the first and second embodiments, is generated at the tip portion of the chip 2. It is possible to generate measurement near-field light (second near-field light) 6a, 6b, and 6c at the tips of 1 and 15 that are much larger than those of the first and second embodiments. Furthermore, the near-field light for measurement (second near-field light) 6a, 6b, and 6c is generated by the near-field light for excitation (first near-field light) 10 localized in the range of several hundred nm. Therefore, unnecessary scattered light is drastically reduced and background noise is greatly reduced. As a result, it is possible to obtain a near-field light image having a resolution of nanometer order with improved SN ratio, contrast, and measurement reproducibility. Furthermore, in the present embodiment, a near-field image with a resolution of nanometer order can be obtained at three RGB wavelengths, so that there is an advantage that the material can be easily identified.

In this embodiment, the wavelength can be increased from 3 wavelengths to 4 wavelengths, or near-field spectroscopic measurement can be performed using white laser light and a spectroscope.
In all the embodiments described above, near-field Raman spectroscopic measurement that detects, for example, a Raman-shifted wavelength instead of the same wavelength as that of the excitation laser beam is also possible.

1 CNT probe 2

Si chip

3, 3 a, 3 b Gold thin film 4

Si cantilever

5, 5 a, 5 b, 5 c

Excitation laser light

6, 6 a, 6 b, 6 c Measurement near-field light (second near-field light)
7, 7a, 7b, 7c Plasmon resonance angle 8 Gold / aluminum film thickness d
9, 9a, 9b,

9c Surface plasmon

10, 10a, 10b, 10c Excitation near-field light (first near-field light)
11

Gold nanoparticles

13, 13a, 13b, 13c Scattered light (propagating light)
14 Metal thin film such as gold, silver or aluminum 15 Si probe, HDC (High Density Carbon) probe, metal probe such as gold, silver or aluminum 18 Si layer film thickness ds
20

Samples

25 and 26

Sample holders

30 and 31 XY piezoelectric element stage 33 Z piezoelectric element stage 34 Piezoelectric element actuator 35 Semiconductor laser 36 Laser light 37 Quadrant sensor 41

Condensing lenses

42 and 46 Detector 43 Light receiving surface 44 1 point 45 Wavelength Separation

optical system

47, 47a, 47b Aluminum

thin film

50, 51 Excitation laser light irradiation system 60 Oscillator 70 Lock-in amplifier 80 Control unit 90 Display 100 Optical lever detection system 110 Scattered light detection system 120 Signal processing / control system

Claims

A measurement probe that relatively scans the sample to be inspected;
An excitation light irradiation system;
An excitation near-field light generation system that generates excitation near-field light in a region including the measurement probe by irradiation of excitation light from the excitation light irradiation system;
A scanning probe microscope comprising: a scattered light detection system that detects scattered light of the measurement near-field light generated between the measurement probe and the sample by the excitation near-field light.
The scanning probe microscope according to claim 1,
The scanning probe microscope characterized in that the excitation near-field light generation system makes the excitation light incident at a plasmon resonance angle.
The scanning probe microscope according to claim 1,
The scanning near-field light generation system generates plasmons by causing plasmon resonance of the excitation light, and generates the excitation near-field light by the plasmons.
The scanning probe microscope according to claim 1,
The near-field light generation system for excitation includes a metal-coated chip, and the excitation light is incident on the chip and further incident on the metal / chip interface at a plasmon resonance angle. .
The scanning probe microscope according to claim 4,
The tip has a triangular pyramid shape,
The measurement probe is provided on the ridge line of the chip,
A scanning probe microscope characterized by irradiating and reflecting the excitation light on a plane of a rear metal thin film of the chip and condensing it on a ridge line of the chip to excite surface plasmons.
The scanning probe microscope according to claim 4,
The tip has a triangular pyramid shape,
The measurement probe is provided on the ridge line of the chip,
A scanning probe microscope characterized by irradiating the excitation light onto a plane of a rear metal thin film of the chip to excite surface plasmons on the plane.
The scanning probe microscope according to claim 1,
The scanning probe microscope characterized in that the scattered light detection system detects scattered light on a sample surface layer of measurement near-field light at the tip of the measurement probe.
The scanning probe microscope according to claim 1,
The scanning light microscope is characterized in that the scattered light detection system detects scattered light transmitted through the sample from scattered light in the sample surface layer of measurement near-field light at the tip of the measurement probe.
The scanning probe microscope according to claim 1,
The excitation light irradiation system irradiates excitation light having a plurality of wavelengths of R, G, and B,
The scanning probe microscope characterized in that the scattered light detection system detects R, G, B components of scattered light of the near-field light for measurement generated between the measurement probe and the sample.
The scanning probe microscope according to claim 9,
The excitation near-field light generating system includes a metal-coated triangular pyramid-shaped chip, and irradiates the excitation light onto the plane of the rear metal thin film of the chip to excite surface plasmons on the plane. And
A scanning probe microscope characterized in that a rear flat portion of the chip is thinned.
The scanning probe microscope according to claim 1,
The scanning probe microscope, wherein the measurement probe is filled with metal nanoparticles or metal nanorods in the axial direction of the measurement probe.
The scanning probe microscope according to claim 1,
The measurement probe has a tip filled with metal nanoparticles, and is a scanning probe microscope.
The scanning probe microscope according to claim 1,
The scanning probe microscope characterized in that the measurement probe has a metal thin film coated on the surface including the tip.
Scan the measurement probe relative to the sample to be inspected,
Generate excitation near-field light in an area including the measurement probe by irradiation of excitation light,
Generate near-field light for measurement between the measurement probe and the sample by the near-field light for excitation,
A sample observation method using a scanning probe microscope, characterized by detecting scattered light of the measurement near-field light.
In the observation method of the sample using the scanning probe microscope according to claim 14,
A sample observation method using a scanning probe microscope, wherein the excitation light is incident at a plasmon resonance angle.
In the observation method of the sample using the scanning probe microscope according to claim 14,
The excitation near-field light is generated by generating plasmons by causing plasmon resonance of the excitation light, and generating the excitation near-field light by the plasmons.